Epoxy resin composition

ABSTRACT

An epoxy resin composition comprising an epoxy resin, either 2-vinyl-4,6-diamino-s-triazine or 2-vinyl-4,6-diamino-s-triazine/isocyanuric acid adduct, and at least one compound selected from dicyandiamide, polyvinyl-p-phenol and specific imidazole compounds. The composition is useful, for example, in inks, insulating paints and adhesives for printed circuit base boards and in copper-clad laminated boards.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an epoxy resin composition which has theability to prevent migration of gold, silver, copper, etc. used ascircuits in electronic component parts and printed base boards, andpossesses excellent heat resistance, chemical resistance, moistureresistance, adhesion and insulation. It is useful, for example, for theproduction of sealing materials for electronic component parts, inks,insulating paints and adhesives for printed circuit base boards, andcopper-clad laminated boards.

2. Description of the Prior Art

Epoxy resins have found widespread use in various industrial fieldsbecause they cure with, for example, aliphatic amines, aromatic amines,tertiary amines, polyamide resins or acid anhydrides to give resinshaving excellent heat resistance, electrical insulation and adhesion.Especially, it is known that blending of a certain imidazole compound, akind of tertiary amine, with an epoxy resin can give a one-package epoxyresin composition having good workability or handlability and beingcapable of giving a cured product having excellent heat resistance (seeU.S. Pat. No. 4,205,156).

With the recent tendency to the smaller sizes, lighter weights andhigher densities of electronic appliances and component parts, epoxyresins for sealing are required to have high insulating property andheat resistance.

Inks and insulating paints for printed circuit base boards andcopper-clad laminated boards have been required likewise to have highinsulation and heat resistance in fine and multilayered printedcircuits. Furthermore, the prevention of migration of silver or copperconstituting the circuits has also been rigorously required. Variousresins have been developed and marketed in an attempt to meet theserequirements, but none have proved to be entirely satisfactory inworkability or handlability or in other properties. For example, theseresins are not entirely satisfactory in regard to curing conditions andpot lives, or have large shrinkage on curing or low adhesion.

SUMMARY OF THE INVENTION

Extensive investigations of the present inventors conducted in view ofthe foregoing state of the art have now led to the discovery of a novelepoxy resin composition which has satisfactory heat resistance,electrical insulation, adhesion, moisture resistance, chemicalresistance and the ability to prevent migration, can be formulated as aone-package system, and can cure at relatively low temperatures.

Thus, according to this invention, there is provided an epoxy resincomposition comprising an epoxy resin, either2-vinyl-4,6-diamino-s-triazine of the following formula ##STR1## or2-vinyl-4,6-diamino-s-triazine isocyanuric acid adduct of the followingformula ##STR2## and at least one compound selected from the groupconsisting of polyvinyl-p-phenol of the following formula ##STR3##wherein n is 25 to 70, dicyandiamide and imidazole compounds representedby the formula ##STR4## wherein R₁ represents a hydrogen atom or acyanoethyl group or 4,6-diaminotriazinyl(-2')ethyl group, R₂ representsa methyl, ethyl, undecyl, heptadecyl or phenyl group, R₄ represents ahydrogen atom or a methyl, hydroxymethyl, benzyl or2-ethyl-5-methylimidazolyl(-4)-methyl group, and R₅ represents ahydrogen atom or a methyl or hydroxymethyl group.

DETAILED DESCRIPTION OF THE INVENTION

The characteristic feature of the present invention is that acomposition having the aforesaid excellent properties can be obtainedfrom an epoxy resin and 2-vinyl-4,6-diamino-s-triazine or2-vinyl-4,6-diamino-s-triazine isocyanuric acid adduct as essentialingredients and at least one third ingredient selected from the groupconsisting of certain imidazole compounds, dicyandiamide andpolyvinyl-p-phenol.

2-Vinyl-4,6-diamino-s-triazine can be synthesized, for example, byreacting biguanide with acryloyl chloride (J. Am. Chem. Soc., 80, 988(1958)), reacting dicyandiamide with beta-dimethylaminopropionitrile(French Pat. No. 1563255), or heating1,2-di(4',6'-diamino-s-triazinyl-(2)')-cyclobutane under reducedpressure (Japanese Patent Publication No. 35068/1971).

2-Vinyl-4,6-diamino-s-triazine/isocyanuric acid adduct can besynthesized by heating the 2-vinyl-4,6-diamino-s-triazine prepared asabove and isocyanuric acid in water in the presence of a polymerizationinhibitor.

Examples of epoxy resins suitably used in this invention includepolyglycidyl ethers of polyhydric phenols such as a diglycidyl ether ofbisphenol A or a diglycidyl ether of bisphenol F, epoxidizedphenolnovolac resins, alicyclic epoxy resins and brominated products ofthese epoxy resins.

Suitable imidazole compounds for use in this invention are compoundsrepresented by the following formula ##STR5## wherein R₁ represents ahydrogen atom or a cyanoethyl group or 4,6-diaminotriazinyl(-2')ethylgroup, R₂ represents a methyl, ethyl, undecyl, heptadecyl or phenylgroup, R₄ represents a hydrogen atom or a methyl, hydroxymethyl, benzylor 2-ethyl-5-methylimidazolyl(-4)-methyl group, and R₅ represents ahydrogen atom or a methyl or hydroxymethyl group.

Examples of the imidazole compounds include2,4-diamino-6-(2'methylimidazolyl-(1)')ethyl-s-triazine,2,4-diamino-6-(2'-methylimidazolyl-(1)')ethyl-s-triazine/isocyanuricacid adduct, 2-phenyl-4,5-dihydroxymethylimidazole,2-phenyl-4-methyl-5-hydroxymethylimidazole,2-phenyl-4-benzyl-5-hydroxymethylimidazole, and4,4'-methylenebis-(2-ethyl-5-methylimidazole). When these imidazolecompounds are blended with liquid epoxy resins, one-package compositionscan be obtained which have excellent storage stability and can be curedat relatively low temperatures of about 150° C.

Other examples of the imidazole compound used in this invention are2-methyl-imidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole,2-undecylimidazole, 2-heptadecylimidazole, 2-phenyl-4-methylimidazole,1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole,and 1-cyanoethyl-2-phenylimidazole. A group of these compounds arepreferably added to epoxy resins immediately before use because blendsof these with liquid epoxy resins have poor storage stability.

The curing mechanism of the composition of this invention is notcertain, but the present inventors theorize as follows. The epoxy resinpolymerizes by the action of the imidazole compound, polyvinyl-p-phenolor dicyandiamide. Simultaneously, the double bonds of2-vinyl-4,6-diamino-s-triazine or2-vinyl-4,6-diamino-s-triazine/isocyanuric acid adduct are cleaved toinduce radical polymerization. Furthermore, the two amino groups on thetriazine ring react with the epoxy resin. It is presumed that thesethree reactions take place almost simultaneously to give a cured producthaving excellent heat resistance and electrical properties.

Now, the invention will be described below with reference to inks andinsulating paints for printed circuit base boards and copper-cladlaminated boards for the production of which the epoxy resin compositionof this invention is useful.

The inks and insulating paints for printed circuit base boards are usedfor the following purposes.

In so-called thick film hybrid integrated circuit base boards obtainedby forming the desired circuit including a silver-, platinum- orpalladium-type conductor containing a glass frit as a binder, aresistor, a condenser etc. on an insulating base board such as a ceramicor glass board by screen printing, and firing the resulting board athigh temperatures or printed circuit base boards obtained by forming thedesired circuit by etching a copper foil on a paper, phenolic resin orglass-epoxy resin laminated board, the required circuit is normallyexposed flat on the surface, and is therefore liable to be corroded bythe adhesion of corrosive substances or moisture contained in theatmosphere.

In order to prevent such an accident by corrosion and to increase thereliability of the circuit, it is the general practice to form aprotective coating, called a permanent resist, on the circuit by screenprinting, etc.

The protective coating used in this case is required to have variousproperties such as electrical insulation, moisture resistance, chemicalresistance, adhesion and hardness. Moreover, since the circuits in theaforesaid thick film hybrid integrated circuit base boards or printedcircuit base boards tend to be minute and complex, plating of nickel,gold, copper, etc. or soldering might cause short-circuiting. It isknown that an attempt is made to prevent this type of accident bycoating a protective paint called a resist ink by screen printing, etc.on those parts which do not require plating, curing the coated film, andthereafter, plating the unprotected parts. The protective paint isrequired to have the functions of ink such as viscosity, roping propertyand thixotropic property suitable for screen printing, etc.Discoloration and migration of a conductor circuit of silver or copperwhich occur upon application of a voltage under high temperature andhigh pressure environmental conditions have become a problem as printedcircuit base boards and the like have been required to have smallersizes, higher densities and higher reliability so as to providesmall-sized and light-weight electronic appliances having highreliability.

Except a triazine resin and a bismaleimide-triazine resin either singlyor in combination, scarcely any resins have been found to be useful forprotective paints.

Known conventional protective paints having the aforesaid properties andfunctions include, for example, paints of the firable glass type, thoseof the heat-curable epoxy resin, phenol resin, melamine resin,epoxy-melamine and silicone resin types, and paints of theultraviolet-curable epoxy-acrylate resin type. Except the paints of theglass type, these protective paints have only an insufficient ability toprevent discoloration and migration of silver or copper conductors. Theaforesaid triazine resin-type and biamalimide-triazine resin-typeprotective paints are not satisfactory with regard to curing conditionsand pot lives.

It has now been found in accordance with this invention that theaforesaid defects can be eliminated by uniformly dispersing 10 to 40parts by weight, per 100 parts by weight of the epoxy resin, ofpolyvinyl-p-phenol having an average degree of polymerization of 25 to70 and a particle diameter of 200 to 300 mesh and 20 to 100 parts byweight, per 100 parts by weight of the epoxy resin, of a filler in anepoxy resin composition comprising the epoxy resin, the imidazolecompound, and either 2-vinyl-4,6-diamino-s-triazine or2-vinyl-4,6-diamino-s-triazine/isocyanuric acid adduct.

The resulting composition is a one-package epoxy resin compositionhaving good storage stability and can be used as a protective paint forthick film hybrid integrated circuit base boards, printed circuit baseboards, and the like or an insulating layer for multiple wirings.

As required, a coloring pigment may be added to the composition of thisinvention. It is also possible to add a thixotropy-imparting agent, adefoamer or a surface flowability adjusting agent in order to impartscreen printing adaptability.

The addition of polyvinyl-p-phenol can accelerate the curing of thecomposition and increase its adhesion to a base board.

With formulations having unsatisfactory storage stability, thecomposition of this invention may be used as a two-package system.Specifically, a package (A) is prepared by uniformly mixing the epoxyresin with 2-vinyl-4,6-diamino-s-triazine or2-vinyl-4,6-diamino-s-triazine/isocyanuric acid adduct and a filler, anda package (B) is prepared by dissolving polyvinyl-p-phenol and theimidazole compound in a suitable amount of an organic solvent such asbutyl carbitol acetate. The packages (A) and (B) are mixed immediatelybefore use.

Copper-clad glass-epoxy resin laminated boards have long been used inthe field of industrial machines and appliances. Since, the spacings inprinted circuits have recently become narrower and an increased numberof components of smaller sizes have been mounted on the circuits, thebase boards have been stringently required to have excellent heatresistance, electrical properties at high temperatures, and migrationpreventing property. Polymide resins or maleimide resins are used asresins for copper-clad laminates requiring these properties. Theseresins have excellent heat resistance and electrical properties, butsolvents therefore are limited. For example, an expensive and highboiling (meaning the difficulty of solvent removal) solvent such asN-methylpyrrolidone has to be used, and curing temperatures of at least200° C. are required.

A copper-clad laminated board having excellent heat resistance andelectrical properties and the excellent ability to present coppermigration can be produced by dissolving a composition comprising theepoxy resin, 2-vinyl-4,6-diamino-s-triazine, the imidazole compound anddicyandiamide in methyl ethyl ketone or methyl Cellosolve, impregnatingthe solution in a substrate, removing the solvent, and bonding copperfoils to the substrate under heat and pressure.

The following examples illustrate the present invention morespecifically.

EXAMPLES 1 AND 2 AND COMPARATIVE EXAMPLE 1

Two parts by weight of2,4-diamino-6-(2'-methylimidazolyl-(1))-ethyl-s-triazine or a curingagent was added to 100 parts by weight of an epoxy resin (EPIKOTE 828(Yuka Shell), and further 20 parts by weight of2-vinyl-4,6-diamino-s-triazine or2-vinyl-4,6-diamino-s-triazine/isocyanuric acid adduct was added.

For comparison, the triazine compound (20 parts) was not added(Comparative Example 1).

Each of the compositions was cured under heat, and the properties of thecured product were measured. The results are shown in Table 1.

                  TABLE 1                                                         ______________________________________                                                                       Compara-                                                                      tive                                                          Example                                                                              Example  Example                                                       1      2        1                                              ______________________________________                                        Formulation (parts by weight)                                                 Epoxy resin      100      100      100                                        Imidazole compound                                                                              2        2        2                                         2-Vinyl-4,6-diamino-s-triazine                                                                  20      --       --                                         2-Vinyl-4,6-diamino-s-triazine/                                                                --        20      --                                         isocyanuric acid adduct                                                       Curing conditions                                                                              100° C./4 hr + 180° C./2 hr                    Glass transition point (°C.)                                                            153      150       84                                        (TMA method)                                                                  Volume resistivity (ohms-cm)                                                   25° C.   3 × 10.sup.15                                                                    6 × 10.sup.15                                                                    4 × 10.sup.15                        100° C.   2 × 10.sup.13                                                                    4 × 10.sup.13                                                                    9 × 10.sup.12                        150° C.   2 × 10.sup.12                                                                    3 × 10.sup.11                                                                    2 × 10.sup.10                        Dielectric constant 30 Hz                                                      25° C.   3.50     3.49     3.56                                       100° C.   3.74     3.98     4.43                                       150° C.   5.05     5.05     30.80                                      ______________________________________                                    

EXAMPLES 3 TO 12 AND COMPARATIVE EXAMPLES 2 TO 4

In these examples, one-package inks for printed circuit base boards wereprepared using 2-vinyl-4,6-diamino-s-triazine (or2-vinyl-4,6-diamino-s-triazine/isocyanuric acid adduct) in accordancewith the formulations indicated in Table 2.

The gel time and storage stability of each of the ink compositions weretested, and the results are given in Table 3.

Each of the ink compositions was coated to a thickness of 20 microns byscreen printing, and heating it at 150° C. for 15 minutes to form acured film. Various properties of the cured film were measured, and theresults are shown in Table 4.

                                      TABLE 2                                     __________________________________________________________________________                                                             Comparative                                 Example                           Example              Composition (parts by weight)                                                                        3   4   5   6  7  8   9   10  11                                                                              12                                                                              2 3 4                __________________________________________________________________________      Epoxy resin:                                                                  Epikote #828 (Yuka Shell)                                                                          100 100 100       100 100 100                            YD128 (Toto Chemical Co.)        70 70             70                                                                              70                                                                              70                                                                              70                                                                              70                 EOCN-1025 (Nihon Kayaku Co.)     30 30             30                                                                              30                                                                              30                                                                              30                                                                              30                 Curing agent                                                                  2,4-Diamino-6-(2'methylimi-         7                 5                                                                               7                     dazolyl-(1'))-ethyl-s-triazine/                                               isocyanuric acid adduct                                                       2,4-Diamino-6-(2'-methylimi-                                                                       1   1   1.5 6     1   1   1    5     5                                                                               6                 dazolyl-(1'))-ethyl-s-triazine                                                Dicyandiamide                                               2                 2-Vinyl-4,6-diamino-s-triazine                                                                     10  10  15  10 10                                        2-Vinyl-4,6-diamino-s-triazine/        10  10  20  10                                                                              10                       isocyanuric acid adduct                                                       Polyvinyl-p-phenol (Resin M,                                                                       20  10  10  10 10 20  10  10  10                                                                              10                       Maruzen Oil Co., Ltd.)                                                        Filler:                                                                       Talc                 20  20  20        20  20  20                             Barium sulfate       60  60  60  60 30 60  60  60  60                                                                              30                                                                              30                                                                              30                                                                              60                 Mica                             20 10             20                                                                              10                                                                              10                                                                              10                                                                              20                 Dispersant:                                                                   Disparon NS-30 (Kusumoto Chemical Co.)                                                             2   2   2         2   2   2                              Disparon NS-30 #230 (Kusumoto Chemical                                                                         0.3                                                                              0.3            0.3                                                                             0.3                                                                             0.3                                                                             0.3                                                                             0.3                Co.)                                                                          Disparon NS-30 #1900 (Kusumoto Chemical                  0.3                  Co.)                                                                          Disparon NS-30 #1930 (Kusumoto Chemical                                                                        0.3                                                                              0.3            0.3                                                                             0.3                                                                             0.3 0.3                Co.)                                                                          Flow adjusting agent:                                                         Aerosil #300 (Japan Aerosil Co.) 2  2               2                                                                               2                                                                               2                                                                               2                                                                               2                 Flow adjusting aid:                                                           Butyl carbitol acetate                                                                             20  10  10        20  10  10                             Cellosolve acetate               5                  5   5                                                                               5                   Xylene                              5                 5     5                 Defoamer:                                                                     KS603 (Shin-etsu Chemical Co., Ltd)                                                                0.5 0.5 0.5       0.5 0.5 0.5                          __________________________________________________________________________

                  TABLE 3                                                         ______________________________________                                        Example (Ex.)                                                                              Gel time   Storage stability (*2)                                or Comparative                                                                             (seconds)  25° C.                                                                           40° C.                               Example (CEx.)                                                                             (*1)       (months)  (days)                                      ______________________________________                                        Ex. 3        95         2         10                                          Ex. 4        95         2         10                                          Ex. 5        105        2         10                                          Ex. 6        70         1          6                                          Ex. 7        50         1          6                                          Ex. 8        95         2         10                                          Ex. 9        95         2         10                                          Ex. 10       90         2         10                                          Ex. 11       80         1          6                                          Ex. 12       60         1          6                                          CEx. 2       80         2         20                                          CEx. 3       75         1         10                                          CEx. 4       80         1          6                                          ______________________________________                                         (*1): Measured by the hot plate method. About 0.3 g of the composition wa     placed on a hot plate kept at 150° C., and spread thin by a            metallic spatula, and the time which elapsed until no roping occurred         between the spatula and the composition was determined and defined as the     gel time.                                                                     (*2): The time which elapsed until the viscosity of the composition           measured by a Btype rotary viscometer reached twice that in the initial       stage was measured, and defined as the storage stability.                

                                      TABLE 4                                     __________________________________________________________________________    Resistance to migration.sup.( *.sup.3)           Chemical resis-              Cu conductor Ag conductor           Electrical                                                                           Heat resis-                                                                         tance.sup.( *.sup.9)                                                                    Hard-              Ex. or                                                                            circuit on                                                                             circuit on Ag conductor circuit                                                                      insulation                                                                           tance to                                                                            10%  10%  ness               CEx.                                                                              XPC substrate.sup.( *.sup.4)                                                           XPC substrate.sup.( *.sup.5)                                                             on ceramic substrate.sup.( *.sup.6)                                                       (ohm-cm).sup.( *.sup.7)                                                              solder.sup.( *.sup.8)                                                               H.sub.2 SO.sub.4                                                                   NaOH (H).sup.(                                                                     *.sup.10)          __________________________________________________________________________    Ex. 3                                                                             no change                                                                              no change  no change   >10.sup.4                                                                            no change                                                                           no   no   >7                                                                  change                                                                             change                  Ex. 4                                                                             "        "          "           "      "     no   no   "                                                                   change                                                                             change                  Ex. 5                                                                             "        "          "           "      "     no   no   "                                                                   change                                                                             change                  Ex. 6                                                                             "        "          "           "      "     no   no   "                                                                   change                                                                             change                  Ex. 7                                                                             "        "          "           "      "     no   no   "                                                                   change                                                                             change                  Ex. 8                                                                             "        "          "           "      "     no   no   "                                                                   change                                                                             change                  Ex. 9                                                                             "        "          "           "      "     no   no   "                                                                   change                                                                             change                   Ex. 10                                                                           "        "          "           "      "     no   no   "                                                                   change                                                                             change                   Ex. 11                                                                           "        "          "           "      "     no   no   "                                                                   change                                                                             change                   Ex. 12                                                                           "        "          "           "      "     no   no   "                                                                   change                                                                             change                  CEx. 2                                                                            Cathode side                                                                           Anode side cir-                                                                          Anode side circuit                                                                        >10.sup.4                                                                            no change                                                                           peeling                                                                            no   >7                     circuit disco-                                                                         cuit discolored 24                                                                       discolored 200 hours     occurred                                                                           change                      lored 100 hours                                                                        hours later, and                                                                         later                                                     later    the discolored part                                                           disappeared 50 hours                                                          later                                                            CEx. 3                                                                            Cathode side                                                                           Anode side cir-                                                                          Anode side circuit                                                                        "      "     peeling                                                                            no   "                      circuit disco-                                                                         cuit discolored 24                                                                       discolored 200 hours     occurred                                                                           change                      lored 100 hours                                                                        hours later, and                                                                         later                                                     later    the discolored part                                                           disappeared 50 hours                                                          later                                                            CEx. 4                                                                            Cathode side                                                                           Anode side cir-                                                                          Anode side circuit                                                                        "      "     peeling                                                                            no   "                      circuit disco-                                                                         cuit discolored 24                                                                       discolored 200 hours     occurred                                                                           change                      lored 100 hours                                                                        hours later, and                                                                         later                                                     later    the discolored part                                                           disappeared 50 hours                                                          later                                                            __________________________________________________________________________    .sup.( *.sup.3) Migration in the test specimen was examined every             predetermined time at a temperature of 60° C., a humidity of 95%       and an applied                                                                voltage (DC) of 30 V.                                                         .sup.( *.sup.4) A copper clad XPC laminate in accordance with the NEMA        standards was used. The copper foil was etched away to form a                 comb-like electrode circuit with a conductor line in width of 0.5 mm and      an interconductor spacing of 0.3 mm. The composition was                      screen-printed on the circuit and cured under heat. The resulting test        specimen was left to stand for 500 hours under the aforesaid                  conditions.                                                                   .sup. ( *.sup.5) By screen printing, a comb-like electrode circuit with a     conductive line in width of 0.5 mm and an interconductor spacing of 0.3       mm                                                                            was formed from a silver powder-phenolic resin paste on an XPC laminate       in accordance with the NEMA standards, and baked at                           150° C. for 30 minutes. Then, the composition was screen-printed       on the circuit, and cured under heat. The resulting test specimen was         left to stand for 100 hours under the conditions indicated in .sup.(          *.sup.3) above.                                                               .sup.( *.sup.6) By screen printing, a comb-like electrode circuit with a      conductor line in width of 1 mm and an interconductor spacing of 0.5 mm       was formed from a silver-palladium powder glass paste on a ceramic            substrate, and fired at 700° C. for 2 hours. The composition was       screen-printed on the circuit and cured under heat. The resulting test        specimen was left to stand for 5 hours under the conditions                   indicated in .sup.( *.sup.3) above.                                           .sup.( *.sup.7) The test specimen was prepared by screen-printing the         composition on an aluminum plate to form a protective film in accordance      with JIS-C-2103.                                                              .sup.( *.sup.8) The test specimen prepared by the method of .sup.(            *.sup.4) above was dipped for 30 seconds in a molten solder bath at           260° C., and then observed                                             for blisters, peeling, etc. on the surface of the coated film. Then, the      specimen was subjected to a crosscut peeling test in accordance               with JIS-D-0202.                                                              .sup.( *.sup.9) The test specimen prepared by the method of .sup.(            *.sup.4) above was immersed for 120 hours in a 10% sulfuric acid solution     or a 10% sodium                                                               hydroxide solution, and then a change in the coated film was observed.        .sup.( *.sup.10) The pencil hardness of the test specimen prepared by the     method .sup.( *.sup.4) was measured in accordance with JIS-D-0202.        

EXAMPLES 13 TO 15 AND COMPARATIVE EXAMPLE 5

Two-package inks for printed circuit base boards were prepared inaccordance with the formulations indicated in Table 5.

The mixing ratio of package A and package B should be determinedaccording to the desired performance. In these examples, the weightratio of package A to package B was adjusted to 100:13.6.

For comparison, a commercial ultraviolet-curable composition (SolderResist UR3000, a trade name for a product of Sanwa Chemical IndustryCo., Ltd.) was used (Comparative Example 5).

                                      TABLE 5                                     __________________________________________________________________________                           Example  Comparative                                   Package                                                                            Composition (parts by weight)                                                                   13 14 15 Example 5                                     __________________________________________________________________________    A    1.                                                                              Epoxy resin (EPIKOTE #828)                                                                    100                                                                              100                                                                              100                                                                              Commercial                                         2.                                                                              2-Vinyl-4,6-diamino-s-triazine                                                                15 15 15 ultraviolet-                                       3.                                                                              Fillers: Talc   20 20 20 curable                                              Barium sulfate  60 60 60 composition                                        4.                                                                              Dispersant: Disparon NS-30                                                                     2  2  2 (Solder                                       B    5.                                                                              Flow adjusting aid: butyl-                                                                    20 10 10 Resist                                               carbitol acetate         UR3000)                                            6.                                                                              Polyvinyl-p-phenol (Maruzen                                                                   20 10 10                                                      Resin M)                                                                    7.                                                                              Curing agent                                                                  2,4-Diamino-6-(2'-methylimida-                                                                7.5                                                                              -- --                                                      zolyl-(1'))-ethyl-s-triazine                                                  2,4-Diamino-6-(2'-methylimida-                                                                -- 7.5                                                                              --                                                      zolyl-(1'))-ethyl-s-triazine/                                                 isocyanuric acid adduct                                                       2-Ethyl-4-methyl-imidazole                                                                    -- --  3                                                    8.                                                                              Defoamer KS603 (Shin-etsu                                                                     0.5                                                                              0.5                                                                              0.5                                                     Chemical)                                                              __________________________________________________________________________

The properties of the ink compositions were tested and the results areshown in Table 6. In Table 6, the gel time and the storage stability(pot life) were measured in the same way as indicated in the footnotesto Table 3.

                  TABLE 6                                                         ______________________________________                                        Example (Ex.)                                                                             Gel time  Storage stability (*2)                                  or Comparative                                                                            (*1)      5° C.                                                                           25° C.                                                                         40° C.                          Example (CEx.)                                                                            (seconds) (months) (days)  (days)                                 ______________________________________                                        Ex. 13      25        4 (*b)   4 (*c)  2 (*c)                                 Ex. 14      35        4 (*b)   5 (*c)  2 (*c)                                 Ex. 15      20        4 (*b)   1 (*c)  2 (*c)                                 CEx. 5      20 (*a)   3        --      --                                     ______________________________________                                         (*a): Three 80 W/cm ozoneless highpressure mercury lamps were used for        irradiation. The oven passing rate was 4 m/min.                               (*b): Packages A and B were stored independently.                             (*c): The pot life of a mixture of predetermined amounts of packages A an     B.                                                                       

Each of the compositions was coated to a film thickness of 20 microns byscreen printing, and then cured at 150° C. for 15 minutes. Theultraviolet-curable ink of Comparative Example 5 was cured by usingthree 80 W/cm ozoneless high-pressure mercury lamps (speed 4 m/min.).

The properties of the cured products were tested in the same way asindicated in the footnotes to Table 4. The results are summarized inTable 7.

                                      TABLE 7                                     __________________________________________________________________________                                                     Chemical resis-              Cu conductor Ag conductor           Electrical                                                                           Heat resis-                                                                         tance.sup.( *.sup.9)         Ex. or                                                                            circuit on                                                                             circuit on Ag conductor circuit                                                                      insulation                                                                           tance to                                                                            10%  10% Hardness            CEx.                                                                              XPC substrate.sup.( *.sup.4)                                                           XPC substrate.sup.( *.sup.5)                                                             on ceramic substrate.sup.( *.sup.6)                                                       (ohm-cm).sup.( *.sup.7)                                                              solder.sup.( *.sup.8)                                                               H.sub.2 SO.sub.4                                                                   NaOH                                                                              (H).sup.(                                                                     *.sup.10)           __________________________________________________________________________    Ex. 13                                                                            no change                                                                              no change  no change   >10.sup.4                                                                            no change                                                                           no   no  >7                                                                   change                                                                             change                  Ex. 14                                                                            "        "          "           "      "     no   no  "                                                                    change                                                                             change                  Ex. 15                                                                            "        "          "           "      "     no   no  "                                                                    change                                                                             change                  CEx. 5                                                                            Cathode side                                                                           Anode side circuit                                                                       Anode side circuit                                                                        "      "     peeled                                                                             peeled                                                                            >3                      circuit dis-                                                                           discolored 24 hours                                                                      discolored 200                                            colored 100                                                                            later, and the                                                                           hours later                                               hours later                                                                            discolored part                                                               disappeared 50                                                                hours later                                                      __________________________________________________________________________

EXAMPLES 16 AND 17 AND COMPARATIVE EXAMPLE 6

In each run, a composition was prepred in accordance with theformulation shown in Table 8.

                  TABLE 8                                                         ______________________________________                                                          Exam-   Exam-                                               Ingredients       ple     ple     Comparative                                 (parts by weight) 16      17      Example 6                                   ______________________________________                                        Epomic R301-M80 (Mitsui Petro-                                                                  37.5            100                                         chemical Industries (*d)                                                      Epikote DX2480B70 (Yuka   100                                                 Shell) (*e)                                                                   Epikote #828 (Yuka Shell)                                                                       20      10                                                  2-Vinyl-4,6-diamino-s-                                                                          10      8                                                   triazine (*f)                                                                 Dicyandiamide             6.4     6.4                                         2-Ethyl-4-methylimidazole                                                                       0.7     0.8     0.8                                         Methyl ethyl ketone                                                                             71.2    40                                                  Methyl Cellosolve         53.1    62.8                                        ______________________________________                                         (*d): Epomic R301M80 is a 80% by weight methyl ethyl ketone solution of a     epibis type solid epoxy resin.                                                (*e): Epikote DX248B70 is a 70% by weight methyl ethyl ketone solution of     brominated epoxy resin (bromine content 24-26%).                              (*f): 2Vinyl-4,6-diamino-s-triazine was kneaded in advance with Epikote       #828 on a threeroll mill and dispersed until the particle diameter became     less than 5 microns.                                                     

The composition in solution was impregnated with glass woven cloths(0.18 mm thick) treated with aminosilane, and dried in the air to removethe solvent.

The composition was pre-cured at 90° C. for 3 minutes (for Examples 16and 17) or 150° C. for 3 minutes (for Comparative Example 6) to prepareprepregs.

Eight such prepregs were laid one on top of another, and copper foils(35 microns) were placed over the top and bottom of the assembly. Theentire assembly was compressed at 170° C. and 50 to 60 kg/cm² for 90minutes, and then heat-treated at 200° C. for 60 minutes to cure theepoxy composition.

The properties of the resulting copper-clad laminated board weremeasured, and the results are shown in Table 9.

                  TABLE 9                                                         ______________________________________                                                        Example  Example  Comparative                                 Properties      16       17       Example 6                                   ______________________________________                                        Glass transition point                                                                         185      180     150                                         (°C.) (*11)                                                            Solder heat resistance                                                                        >180     >180      30                                         (seconds) (*12)                                                               Peel strength of the copper                                                                    1.8      1.7     1.8                                         foils (kg/cm) (*13)                                                           Flame retardance (seconds)                                                                    burned   .sup. 6  burned                                      (*14)                                                                         ______________________________________                                         (*11): The glass transition point of the copperclad laminated board was       measured by the TBA method after the copper foils were removed from it by     etching and a thin piece was cut out from the board.                          (*12): A square piece with each side measuring 25 mm was prepared from th     copperclad laminated board, and caused to float on a solder bath at           260° C. It was observed for changes such as blisters.                  (*13): The peel strength of the copper foils is the strength measured whe     the copper foil was peeled perpendicularly from a 10 mm width test piece      of the copperclad laminated board at a speed of 5 mm/min.                     (*14): Measured by the vertical method of UL Standards 94.               

What is claimed is:
 1. An epoxy resin composition comprising an epoxyresin, either 2-vinyl-4,6-diamino-s-triazine or2-vinyl-4,6-diamino-s-triazine/isocyanuric acid adduct, and at least onecompound selected from the group consisting of dicyandiamide,polyvinyl-p-phenol, and imidazole compounds represented by the followingformula ##STR6## wherein R₁ represents a hydrogen atom or a cyanoethylgroup or 4,6-diaminotriazinyl(-2')ethyl group, R₂ represents a methyl,ethyl, undecyl, heptadecyl or phenyl group, R₄ represents a hydrogenatom or a methyl, hydroxymethyl, benzyl or2-ethyl-5-methylimidazolyl(-4)-methyl group, and R₅ represents ahydrogen atom or a methyl or hydroxymethyl group.
 2. An epoxy resincomposition according to claim 1 which comprises 100 parts by weight ofthe epoxy resin, 5 to 50 parts by weight of either2-vinyl-4,6-diamino-s-triazine or2-vinyl-4,6-diamino-s-triazine/isocyanuric acid adduct, and at least onecompound selected from the group consisting of 1 to 20 parts by weightof dicyandiamide, 10 to 40 parts by weight of polyvinyl-p-phenol, and0.025 to 10 parts by weight of the imidazole compounds.
 3. An epoxyresin composition according to claim 1 which comprises the epoxy resin,2-vinyl-4,6-diamino-s-triazine and the imidazole compound.
 4. An epoxyresin composition according to claim 1 which comprises the epoxy resin,2-vinyl-4,6-diamino-s-triazine, the imidazole compound anddicyandiamide.
 5. An epoxy resin composition according to claim 1 whichcomprises the epoxy resin, 2-vinyl-4,6-diamino-s-triazine, the imidazolecompound and polyvinyl-p-phenol.
 6. An epoxy resin composition accordingto claim 1 which comprises the epoxy resin, the2-vinyl-4,6-diamino-s-triazine/isocyanuric acid adduct and the imidazolecompound.
 7. An epoxy resin composition according to claim 1 whichcomprises the epoxy resin, the2-vinyl-4,6-diamino-s-triazine/isocyanuric acid adduct, the imidazolecompound and polyvinyl-p-phenol.